Frequently Asked Questions

It depends on what gets foamed. A house that size rarely needs foam on every surface. National guides put whole-house spray foam at about $8,000 to $20,000 (HomeGuide) or $10,000 to $30,000 (Fixr). Most Detroit homes get better value from foam in a few key spots, like the rim joist, kneewalls and roof deck areas, plus blown-in insulation elsewhere.

HomeGuide lists about $1.50 to $3.50 per square foot for open-cell and $3.00 to $5.00 for closed-cell, installed. Thickness drives the price, so a 5-inch roof deck costs more per square foot than a 2-inch rim joist. Your written estimate is the number you pay.

Most concerns trace back to poor installs: foam sprayed onto a roof deck that hides a leak or rotting sheathing, or foam mixed or applied wrong that leaves an odor. Foam that is planned for the space, applied at the right thickness and left to cure properly does not have those problems. We check for leaks and moisture first and write down what was installed where.

Some buyers and inspectors ask more questions about foam on the underside of a roof, because it makes the decking harder to inspect. Keeping your quote and invoice, with the product, thickness and areas listed, gives a future buyer real answers. Foam on rim joists and basement walls rarely raises questions.

We do not offer free foam, and we would be wary of anyone who does. What does exist is DTE's insulation rebate program for customers whose heat DTE provides, which lists set amounts per area. Check DTE's current page for amounts and deadlines.

If the budget only covers one, the attic usually comes first because warm air escapes upward and the attic floor holds the biggest leaks. The rim joist is a close second and costs much less. We often do both on the same visit, since sealing both ends is what stops the draft through the house.

Closed-cell. Basement walls and rim joists stay cool and slightly damp, and closed-cell foam resists moisture and slows vapor. Open-cell can hold moisture against cold concrete or wood.

Foam that is installed correctly and kept dry stays in place for the life of the house. It does not settle the way loose fill can. Problems usually come from roof leaks or plumbing leaks behind it, which is why we check for them first.

Standard spray foam needs an open cavity. For closed walls in older homes we usually use dense-pack cellulose or an injection foam through small holes. See our wall insulation page for how that works.

In living spaces and many attics and basements, foam needs a thermal or ignition barrier such as drywall or a listed coating. The requirement depends on the product and how the space is used. We tell you what applies before we start.

The Michigan code in force lists R-38 for ceilings in Zone 5A. The Department of Energy suggests R-60 for a bare attic in Zone 5, or adding R-49 over 3 to 4 inches. In blown cellulose that is roughly 13 to 17 inches or more, depending on the product.

Insulation helps, but air sealing matters more. Ice dams come from warm house air reaching the roof deck. Sealing the attic floor and keeping the eaves vented addresses the cause.

Usually, if the old insulation is dry and clean. Wet, moldy or rodent-damaged insulation should come out. Loose fill that may be vermiculite should be tested first.

DTE's 2026 insulation page lists $600 for roof and attic insulation of at least 500 square feet when DTE is the primary provider of your heat. Applications have deadlines and funds are limited, so check the page.

Often, yes. The rim runs around the whole house and is usually bare or poorly sealed. HomeGuide puts typical rim joist foam at $2,000 to $2,500, and DTE lists a $50 rebate for rim joists when it supplies your heat.

Not until the source of the water is fixed. Foam can go on dry concrete that has normal seasonal dampness, but walls with active seepage need waterproofing or drainage work first.

Usually, in a basement that is or could be used as living space, foam needs a thermal barrier such as drywall. Some products have listed coatings for certain uses. We tell you what applies before we start.

That is the rim joist. Each bay between floor joists needs to be sealed, including bays behind ducts and pipes. Missing even a few bays leaves cold spots.

Yes. We drill small holes, blow dense-pack cellulose or inject foam into each bay, and patch the holes. Outside, we can often work under a lifted course of siding instead.

Loose fill blown at low density can settle. Dense-pack cellulose is blown at a much higher density to resist settling and slow air movement.

It depends on whether the brick is veneer over a wood frame or solid masonry. Veneer walls usually can be filled. Solid masonry needs a careful look because it changes how the brick dries through freeze-thaw cycles.

DTE's 2026 insulation page lists $125 for above-grade walls of 250 square feet or more, for homes where DTE is the primary heat provider. Check the page for current terms.

In a story-and-a-half house, that room is surrounded by kneewalls, slopes and side attics that are often poorly insulated and leak air. Outside temperatures reach the room from almost every side.

It is the short wall in an upstairs room under a sloped roof, usually 3 to 5 feet tall, with an unheated side attic behind it. It often has a small door for storage access.

It is a good option when ducts or storage are in the side attics or the slopes are too tight to insulate well. It costs more than insulating the kneewalls and floors, so we price both.

DTE's 2026 page lists $25 for kneewall insulation of at least 100 square feet, plus $600 for roof and attic insulation over 500 square feet, when DTE is the primary heat provider.

Not always. Dry, clean insulation can stay and be topped up. Wet, moldy, rodent-damaged or badly compressed insulation should come out, and removal also makes thorough air sealing much easier.

For a typical attic, removal usually takes a day, sometimes less, depending on the amount and access. Sealing and new insulation can follow the same day or the next.

Do not disturb it. Have it tested. If it contains asbestos, it needs to be removed by an abatement contractor before other attic work.

Yes, but it is slow work because foam bonds to the wood. Expect a higher cost per square foot than loose fill.